Characterization of surfactant partitioning in polyelectrolyte#surfactant nanorod aggregates observed with a surfactant-specific electrode

Self-assembled polymer-surfactant aggregates offer an inexpensive and robust approach to controlling the nanoscale structure of materials in solution. However, complete understanding of the partitioning of different species is required for design and engineering of these structures. In this work, the surfactant partitioning of an oppositely charged polyelectrolyte-surfactant (PES) aggregate system in aqueous solution is characterized using a surfactant-specific coated-wire electrode. Previous work has shown that the structure of these aggregates is sensitive to the surfactant partitioning behavior, so characterizing this behavior is vital in controlling the aggregate structure. Due to our synthesis procedure, no small counterions (salts) are present in the system; therefore, the electrolyte concentration can be controlled very accurately and the effect of background electrolyte on surfactant partitioning behavior characterized. A simple model describing the surfactant partitioning in the system is presented and compared to the observed results. Results provide the tools to control the length and surface charge of these rodlike nanoparticles through overall composition.